Eglwys Mynydd Seion

Early Gothic style. Built of rock-faced black basaltic stone, probably from Penmaenmawr, with sharply contrasting Bath oolitic limestone dressings, and a slate roof. The main S front has a gabled central section with 3 close-set Gothic 2-light windows, a roundel in the apex, and lean-to narthex-porch, gabled over the central moulded doorcase, which is angled at the head. Buttresses at either side of the door rise as pinnacles, and triple windows each side with pierced balustrade over. The central section is extended each side as 2-storey stair wings; similar 2-light windows with quatrefoil heads, the upper windows gabled.

The E side, facing Chapel Street, has three 2-light windows beyond the stair wing, separated by buttresses, and gabled transepts at the N end, having triple tall lancets with quatrefoil heads and a gable oculus. The N end terminates in a polygonal apse with a hipped roof, and almost detached, a vestry set at right angles under a separate roof.

The main body of the chapel is of 4 bays, slightly tapering to the N, before the transepts. Plastered walls and a six-sided boarded vaulted ceiling on trusses extended down by wall shafts to corbels. A west gallery stands on octagonal cast iron columns. The arch behind the pulpit contains an organ and console by P Conacher, with a Gothic case. The octagonal pulpit is set forward from its access gallery which has flights of 5 steps at each end, all set in a semi-circular set fawr with a pitch-pine balustrade.

The pews are in pitch pine, set on a slightly raked floor, and laid out in 3 banks, with further pews in the transepts, totaling some 510 places plus the gallery. Doors either side of the organ lead to the vestry and side entrance.

The entrance narthex has patterned stained glass windows, and triple arches supporting the S wall of the chapel.